ROBERT SIEGEL, HOST:
Now to Vienna and the talks there over Iran's nuclear program. Through the weekend and continuing today, the U.S., other world powers and Iran have been in tense negotiations and been limiting Iran's ability to develop nuclear weapons in exchange for easing economic sanctions. NPR's Peter Kenyon is covering the talks, and he joins me now from Vienna. Hi, Peter.
PETER KENYON, BYLINE: Hi, Robert.
SIEGEL: What's holding up the talks?
KENYON: Well, when you get to this stage in high stakes negotiations, there are any number of potential complications. We're told they have reduced the list of differences. They've got more to do. We've talked about some of the sticking points in the past. There's a U.N. arms embargo Iran wants lifted, questions of how quickly Iran can modernize its nuclear equipments under a deal, the issue of replacing sanctions if Iran doesn't comply - how quickly that could be done. And also smaller things like language. I mean, the U.N. Security Council's going to have to pass a new resolution. Will it call Iran's nuclear activity illegal? Things like that. And then they've just got to go over every single paragraph, every line and make sure it's airtight and binding, as much as it can be. There's really not much trust here, and this has got to last for years.
SIEGEL: Every single paragraph and every single line in what is reported to be an 80-page agreement in the works - that would imply that they have agreed on most things, wouldn't it?
KENYON: Yes. I'd say the bulk of these 80 or more pages will be technical annexes. The really important details - who has to do exactly what, exactly at what time and how it's going to be verified. But it's pretty clear that a lot of the really important nuclear restrictions the West wants have been agreed for some time. Iran's going to uninstall most of its centrifuges. It's going to get rid of almost all of its nuclear fuel stockpile, and it has to take the core out of its heavy water reactor and several other things. But that may not be the prominent thing we hear in the coming weeks because the critics in Congress and elsewhere are going to be focusing on what's not in the deal.
SIEGEL: And by things not in the agreement, what do critics mean?
KENYON: Well, there's things like the so-called anytime, anywhere inspections by the U.N. or physically dismantling centrifuges instead of uninstalling them. Now, those are the kinds of things critics will be focusing on.
SIEGEL: And now we have the 21st century dimension to this story. As the diplomats have been working on this deal, the Twitterverse has been full of communications about it. Tell us what's going on there.
KENYON: Well, it started when Israeli Prime Minister Benjamin Netanyahu chose today to open a new Twitter account in Farsi. His first message said a nuclear deal would pave the way for an Iranian bomb. It would provide billions of dollars to allow Tehran to increase its terrorist activities. Iranian journalists here in Vienna were kind of amused at first by what they called a silly spelling mistake in that first Netanyahu Farsi message. And then Iran's president, Hassan Rouhani's, office sent out a tweet praising the deal, only to have to yank it back and replace it with another one saying if a deal is reached it's a great thing. So obviously anticipation is energizing both supporters and critics.
SIEGEL: That's NPR's Peter Kenyon at the nuclear talks in Vienna. Peter, thank you.
KENYON: You're welcome, Robert. Transcript provided by NPR, Copyright NPR.